Grinding Tool and Method of Fabricating the Same

ABSTRACT

A grinding tool includes a substrate and a plurality of abrasive particles. The substrate has a first and a second surface and a plurality of holes, each of the holes extending through the substrate and respectively having a first and a second opening on the first and second surface, the second opening being larger than the first opening. The abrasive particles are respectively disposed in the holes and attached to the substrate via a plurality of adhesive portions, each of the abrasive particles having a tip protruding outward from the first surface and a remaining part covered with one of the adhesive portions inside the corresponding hole, wherein the first openings of the holes are smaller than the abrasive particles, and the abrasive particles are respectively retained in the holes. Moreover, embodiments described herein include a method of fabricating a grinding tool.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This U.S. patent application claims priority to Taiwan Patent Application No. 106119428 filed on Jun. 12, 2017, which is incorporated herein by reference.

BACKGROUND 1. Field of the Invention

The present invention relates to grinding tools and fabrication methods thereof.

2. Description of the Related Art

Grinding and/or polishing techniques are generally applied to create a desirable surface roughness or planarity of a rigid part, such as metal, ceramic or glass parts, or semiconductor wafers. To this purpose, the grinding and/or polishing techniques use tools having abrasive elements that can wear the rigid surface.

A well known polishing technique is the chemical mechanical polishing (CMP) technique employed in semiconductor fabrication processes. CMP uses a corrosive chemical slurry in conjunction with a polishing pad to remove undesired residues and planarize a wafer surface, which can be made of ceramic, silicon, glass, sapphire or metal. After the polishing pad is used over a period of time, the grinding action of the polishing pad may diminish. Accordingly, an additional grinding tool (also called “conditioner”) may be typically used to coarsen the surface of the polishing pad for maintaining an optimal grinding efficiency of the polishing pad.

Conventionally, a cutting rate of the grinding tool may be improved by increasing a distribution density of the abrasive elements provided thereon. This requires increasing the quantity of abrasive elements on the grinding tool, which makes the grinding tool more expensive to manufacture.

FIG. 1 is a schematic view illustrating a conventional technique for fabricating a conditioner 1. A mesh plate 13 can be used to position and control the height of a abrasive elements 11 placed in a mold 14. Then a glue or resin 12 can be applied over the abrasive elements 11 inside the mold 14. Pressure and vacuum can be applied so as to reduce the formation of air voids in the glue or resin 12. Once the glue or resin 12 solidifies, it can be removed from the mold 14 to obtain the conditioner 1 shown in FIG. 2 comprised of the abrasive elements 11 adhered to the solidified glue or resin 12. In practice, the aforementioned conditioner 1 may have some disadvantages, e.g., the solidified glue or resin 12 may be subjected to alteration in contact with a corrosive chemical slurry, which may result in the detachment of the abrasive elements 11.

Therefore, there is a need for an improved grinding tool that can be fabricated in a cost-effective manner and reliably attach abrasive elements, and can address at least the foregoing issues.

SUMMARY

The present application describes a grinding tool that can reliably attach abrasive particles, and can be fabricated in a cost-effective manner. The grinding tool includes a substrate and a plurality of abrasive particles. The substrate has a first and a second surface and a plurality of holes, each of the holes extending through the substrate and respectively having a first and a second opening on the first and second surface, the second opening being larger than the first opening. The abrasive particles are respectively disposed in the holes and attached to the substrate via a plurality of adhesive portions, each of the abrasive particles having a tip protruding outward from the first surface and a remaining part covered with one of the adhesive portions inside the corresponding hole, wherein the first openings of the holes are smaller than the abrasive particles, and the abrasive particles are respectively retained in the holes.

The present application further describes a method of fabricating a grinding tool. The method includes providing a substrate having a first and a second surface and a plurality of holes, each of the holes extending through the substrate and respectively having a first and a second opening on the first and second surface, the second opening being larger than the first opening; respectively placing a plurality of abrasive particles in the holes through the second openings thereof, wherein the abrasive particles are generally larger than the first openings and partially protrude outward from the first openings; placing the substrate on a fixed support having a plurality of positioning cavities, the abrasive particles protruding from the first openings being respectively received partially in the positioning cavities; and respectively applying a plurality of adhesive portions through the second openings into the holes, thereby the adhesive portions respectively cover the abrasive particles inside the holes and fixedly attach the abrasive particles to the substrate.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view illustrating a conventional technique for fabricating a conditioner;

FIG. 2 is a schematic cross-sectional view illustrating a conventional conditioner;

FIG. 3 is a schematic top view illustrating an embodiment of a grinding tool;

FIG. 4 is a cross-sectional view illustrating an embodiment of a grinding tool;

FIG. 5 is a cross-sectional view illustrating a variant construction of a grinding tool;

FIG. 6 is a cross-sectional view illustrating another variant construction of a grinding tool;

FIG. 7 is a flowchart of method steps for fabricating a grinding tool; and

FIGS. 8-11 are schematic views illustrating various intermediate stages in the fabrication of a grinding tool.

DETAILED DESCRIPTION OF THE EMBODIMENTS

FIG. 3 is a schematic top view illustrating an embodiment of a grinding tool 2, and FIG. 4 is a cross-sectional view illustrating the grinding tool 2. Referring to FIGS. 3 and 4, the grinding tool 2 can include a substrate 21, and a plurality of abrasive particles 22 fixedly attached to the substrate 21. The substrate 21 may be a single rigid body. The substrate 21 may be made of stiff and chemically stable materials, which can exemplary include metallic materials such as stainless steel, ceramics, and the like. According to an embodiment, the substrate 21 is made of stainless steel so that the grinding tool 2 is less subjected to chemical alteration when it is used in contact with an acid or alkaline slurry. There is no particular limitation imposed on the size of the substrate 21. According to an embodiment, the substrate 21 may be a generally circular disk having a diameter of about 4 inches and a thickness equal to about 2 mm to about 3 mm. The substrate 21 may have two opposite surfaces 211 and 212, the surface 211 being a working surface of the grinding tool 2, and the surface 212 being a non-working surface of the grinding tool 2. The abrasive particles 22 can be distributed across and protrude outward from the surface 211 of the substrate 21.

The abrasive particles 22 can be made of any suitable materials having high hardness. Examples of suitable materials for the abrasive particles 22 may include, without limitation, diamond, cubic boron nitride, aluminum oxide, and silicon carbide. The abrasive particles 22 are not limited in shape, and may exemplary have a hexoctahedron crystalline form. Moreover, the abrasive particles 22 may have any suitable size in accordance with the requisite functions of the grinding tool 2. According to an embodiment, the size of the abrasive particles 22 can exemplary be about 20 to about 30 US mesh, i.e., a mesh screen used to filter the abrasive particles 22 can have about 20 to about 30 openings per square inch, and an average greatest width of the abrasive particles 22 is between about 800 μm and about 1000 μm. According to an embodiment, there may be about 60 to about 300 abrasive particles 22 provided on the substrate 21.

Referring to FIG. 4, the substrate 21 can include a plurality of holes 213. The abrasive particles 22 can be respectively disposed in the holes 213, and can be respectively attached to the substrate 21 via a plurality of adhesive portions 216. Each abrasive particle 22 thereby attached can have a tip 221 protruding from the surface 211 of the substrate 21, and a remaining part entirely covered with the adhesive portion 216 inside the hole 213 of the substrate 21. In other words, the abrasive particles 22 protrude outward from the surface 211 of the substrate 21, but do not protrude from the surface 212 of the substrate 21.

Each hole 213 can extend through the substrate 21, and can respectively form two openings 212A and 211A on the two opposite surfaces 212 and 211. According to an example of construction, the openings 212A and 211A can have circular shapes, and the openings 212A can be larger than the openings 211A. Moreover, the abrasive particles 22 are generally larger than the openings 211A. For example, each opening 211A can have a diameter generally smaller than each abrasive particle 22, e.g., smaller than an average size or average greatest width of the abrasive particles 22. According to an embodiment, the opening 212A can have a diameter between 1 mm and 2 mm, such as 1 mm, and the opening 211A can have a diameter between 0.4 mm and 0.75 mm, such as 750 μm. According to an embodiment, a size ratio (e.g., diameter ratio) between the opening 211A and the opening 212A can be between about 0.2 and about 0.75, e.g., from 0.4 to 0.375. With this differential size configuration, the smaller opening 211A can block passage of the abrasive particle 22 and thereby retain the abrasive particle 22 in the hole 213. As a result, the abrasive particle 22 can be prevented from falling out of the grinding tool 2 during use. Once the abrasive particle 22 is positioned in the hole 213, the abrasive particle 22 can partially protrude outward from the opening 211A on the surface 211 of the substrate 21.

According to an embodiment, each hole 213 can include two hole sections 215 and 214 connected with each other that have different sizes and shapes. The hole section 215 can exemplary have a cylindrical shape, and the other hole section 214 can be exemplary shaped as a truncated cone. The hole section 215 can open on the surface 212 through the opening 212A, and can have an inner sidewall that can be substantially perpendicular to the surface 212. The hole section 214 can open on the surface 211 through the opening 211A, and can have a tapered shape that narrows toward the surface 211. For example, a material angle between an inner sidewall of the hole section 214 and the surface 211 can be between about 70 and about 89 degrees. Because the diameter of the hole section 215 is generally greater than any diameter of the tapered hole section 214, an adhesive material flowed from the hole section 215 toward the hole section 214 to form the adhesive portion 216 can fully fill the hole 213, which can reduce the occurrence of air voids inside the adhesive portion 216. The portion of the abrasive particle 22 received inside the hole 213 is in contact with the adhesive portion 216, which can substantially attach the abrasive particle 22 to the substrate 21. Examples of suitable materials for the adhesive portions 216 can include epoxy, phenolic resins, polyester resins, polyamide resins, polyimide resins, polycarbonate resins, and any combinations thereof.

FIG. 5 is a cross-sectional view illustrating a variant construction of a grinding tool 3. Referring to FIG. 5, the grinding tool 3 can include the substrate 21, the abrasive particles 22 attached to the substrate 21, and a base substrate 31. The base substrate 31 can be provided to further increase the rigidity of the grinding tool 3. The substrate 21 may have the same structure described previously, and the abrasive particles 22 may be attached to the substrate 21 in a similar way. More specifically, the same holes 213 described previously may be provided in the substrate 21 and extend through the two opposite surfaces 211 and 212 of the substrate 21. The abrasive particles 22 can be respectively disposed in the holes 213, and can be respectively attached to the substrate 21 via the adhesive portions 216. Each abrasive particle 22 thereby attached can have a tip 221 protruding from the surface 211 of the substrate 21, and a remaining part entirely covered with the adhesive portion 216 inside the hole 213 of the substrate 21. The base substrate 31 can have a cavity 311 provide on a major surface thereof, and the substrate 21 can be placed in the cavity 311 and attached to the base substrate 31 with the abrasive particles 22 protruding outward. According to an embodiment, a plurality of cavities 311 can be provided on the major surface of the base substrate 31, and multiple substrates 21 with the abrasive particles 22 thereon can be respectively disposed in the cavities 311.

FIG. 6 is a cross-sectional view illustrating another variant construction of a grinding tool 4. Referring to FIG. 6, the grinding tool 4 can include a substrate 41, and a plurality of abrasive particles 22 respectively attached to the substrate 41.

The substrate 41 can may be integrally formed as a single rigid body. In particular, the substrate 41 may be made of a stiff and chemically stable material, which can exemplary include stainless steel, ceramics, and the like. According to an embodiment, the substrate 41 is made of stainless steel so that the grinding tool 4 is less subjected to chemical alteration when it is used in contact with an acid or alkaline slurry. There is no particular limitation imposed on the size of the substrate 41. According to an embodiment, the substrate 41 may be a generally circular disk having a diameter of about 4 inches. Moreover, the substrate 41 may have a thickness greater than the thickness of the substrate 21 described previously so as to increase the rigidity of the grinding tool 4. For example, the thickness of the substrate 41 can be between 5 mm and 6.35 mm.

The substrate 41 may include a plurality of holes 413 extending through two opposite surfaces 411 and 412 of the substrate 41. The abrasive particles 22 can be respectively disposed in the holes 413, and can be respectively attached to the substrate 41 via adhesive portions 416. Each abrasive particle 22 thereby attached can have a tip 421 protruding from the surface 411 of the substrate 41, and a remaining part entirely covered with the adhesive portion 416 inside the hole 413 of the substrate 41. In other words, the abrasive particles 22 partially protrude outward from the surface 411 of the substrate 41, but do not protrude from the surface 412 of the substrate 41.

Referring to FIG. 6, each hole 413 extending through the substrate 41 can respectively have two openings 412A and 411A on the two opposite surfaces 412 and 411. According to an example of construction, the openings 412A and 411A can have circular shapes, and the openings 412A can be larger than the openings 411A. Moreover, the abrasive particles 22 are generally larger than the openings 411A. For example, each opening 411A can have a diameter generally smaller than each abrasive particle 22, e.g., smaller than an average size or average greatest width of the abrasive particles 22. According to an embodiment, the opening 412A can have a diameter between 1 mm and 2 mm, such as 2 mm, and the opening 411A can have a diameter between 0.4 mm and 0.75 mm, such as 750 μm. With this differential size configuration, the smaller opening 411A can block passage of the abrasive particle 22 and thereby retain the abrasive particle 22 in the hole 413. As a result, the abrasive particle 22 can be prevented from falling out of the grinding tool 4 during use. Once the abrasive particle 22 is positioned in the hole 413, the abrasive particle 22 can partially protrude outward from the opening 411A on the surface 411 of the substrate 41.

In the embodiment illustrated in FIG. 6, each hole 413 can include three hole sections 415, 417 and 414 connected with one another, the hole section 417 being located between and connected with the two hole sections 415 and 414. The hole section 415 can open on the surface 412 through the opening 412A, and the hole section 414 can open on the surface 411 through the opening 411A. The hole section 415 can exemplary have a cylindrical shape with an inner sidewall substantially perpendicular to the surface 412. The hole section 417 can have a cylindrical shape with a diameter generally uniform along its axis, which can be exemplary about 1 mm. The hole section 414 can exemplary have a tapered shape (e.g., a truncated cone) that narrows toward the surface 411. For example, a material angle between an inner sidewall of the hole section 414 and the surface 411 can be between about 70 and about 89 degrees. Because the diameter of the hole section 415 is generally greater than the diameter of the hole section 417, and the hole section 417 is generally larger than the hole section 414, an adhesive material flowed from the hole section 415 through the hole section 417 toward the hole section 414 can fully fill the hole 413, which can reduce the occurrence of air voids inside the adhesive portion 416. The portion of the abrasive particle 22 received inside the hole 413 is in contact with the adhesive portion 416, which can substantially attach the abrasive particle 22 to the substrate 41.

FIG. 7 is a flowchart of exemplary method steps for fabricating the grinding tools 2, 3 or 4 described previously. FIGS. 8-11 are schematic views illustrating various intermediate stages in the fabrication of a grinding tool according to the method steps depicted in FIG. 7. Referring to FIGS. 7 and 8, the substrate 21 including the holes 213 can be provided in initial step S110 for fabricating the grinding tool 2 or 3. Each hole 213 is respectively opened on the two opposite surfaces 212 and 211 of the substrate 21 via the two openings 212A and 211A, the opening 212A being larger than the opening 211A.

According to an embodiment, the holes 213 and the openings 212A and 211A may be formed by drilling into the substrate 21 with a machining tool. For example, step S110 can include drilling the larger hole section 215 and the opening 212A through the surface 212 of the substrate 21, and then drilling the smaller hole section 214 and the opening 211A through the surface 211 of the substrate 21. It will be appreciated that other techniques may be used for fabricating the substrate 21 with the holes 213 therein. For example, another embodiment may directly form the substrate 21 with the holes 213 by powder metallurgy, which can include pressing and sintering a metallic powder to form the substrate 21 with the holes 213 therein.

Referring to FIGS. 7 and 9, the abrasive particles 22 in step S120 can be respectively introduced through the openings 212A and placed in the holes 213 of the substrate 21. Because the openings 211A are smaller than the abrasive particles 22, the abrasive particles 22 can be respectively retained in the hole sections 214 of the holes 213.

Referring to FIGS. 7 and 10, in next step S130, the substrate 21 with the abrasive particles 22 thereon can be placed on a fixed support 5 with the surface 211 of the substrate 21 in contact with the fixed support 5. The fixed support 5 can include a plurality of positioning cavities 51 having an accurately controlled depth, and the substrate 21 can be placed on the fixed support 5 with the abrasive particles 22 (in particular the tips 221 thereof) protruding from the openings 211A respectively received at least partially in the positioning cavities 51 and in contact with the bottoms of the positioning cavities 51. As a result, the positions of the abrasive particles 22 in the holes 213 can be adjusted so that the tips 221 of the abrasive particles 22 can protrude from the surface 211 of the substrate 21 with a desirable height. In particular, the tips 221 of the abrasive particles 22 can be thereby level and protrude from the surface 211 of the substrate 21 with a substantially equal height, the remaining parts of the abrasive particles 22 being located inside the holes 213. For example, the depth of the positioning cavities 51 can be between about 0.01 mm and about 0.3 mm, and the tips 221 of the abrasive particles 22 can protrude outward from the surface 211 of the substrate 21 with a height equal to about 100 μm. A grinding tool having a level placement of the abrasive particles 22 may be advantageously used as a conditioner for uniformly grinding an object surface.

Referring to FIGS. 7 and 11, while the substrate 21 is kept in position on the fixed support 5, the adhesive portions 216 in step S140 can be respectively applied through the openings 212A into the holes 213 with an adhesive dispenser 6 for fixedly attaching the abrasive particles 22 to the substrate 21. The quantity of the adhesive material introduced through the openings 212A can be controlled so that the adhesive portions 216 can fully fill the holes 213 and cover the parts of the abrasive particles 22 inside the holes 213. Examples of suitable materials for the adhesive portions 216 can include epoxy, phenolic resins, polyester resins, polyamide resins, polyimide resins, polycarbonate resins, and any combinations thereof.

It will be appreciated that steps S110, S120, S130 and S140 described herein may be likewise applied for fabricating the grinding tool 4 based on the substrate 41 provided with the holes 413. In this case, the substrate 41 with the holes 413 therein can be provided in initial step S110. For example, step S110 can include drilling the hole section 415 in the substrate 41, then drilling the hole section 417 connected with the hole section 415, and eventually drilling the hole section 414 communicating with the hole sections 415 and 417. The hole sections 415 and 414 thereby formed can respectively have the openings 412A and 411A on the two opposite surfaces 412 and 411 of the substrate 41. Subsequently, the abrasive particles 22 in step S120 can be respectively introduced through the openings 412A and placed in the holes 413 of the substrate 41. Step S130 then can be performed to properly position the abrasive particles 22 in the holes 413. Eventually, the adhesive portions 416 in step S140 can be respectively applied through the openings 412A into the holes 413 for fixedly attaching the abrasive particles 22 to the substrate 41.

According to an embodiment, the method steps may further include attaching the substrate 21 with the abrasive particles 22 affixed thereto to the base substrate 31 for forming the grinding tool 3 shown in FIG. 5. The base substrate 31 may include a cavity 311, and the substrate 21 can be positioned and attached in the cavity 311.

Advantages of the structures and method described herein include the ability to fabricate a grinding tool in a cost-effective manner. The grinding tool can include abrasive particles that are affixed to a substrate with adhesive portions substantially free of air voids, which can ensure reliable attachment of the abrasive particles.

Realizations of the grinding tool and its fabrication process have been described in the context of particular embodiments. These embodiments are meant to be illustrative and not limiting. Many variations, modifications, additions, and improvements are possible. These and other variations, modifications, additions, and improvements may fall within the scope of the inventions as defined in the claims that follow. 

What is claimed is:
 1. A grinding tool comprising: a substrate having a first and a second surface and a plurality of holes, each of the holes extending through the substrate and respectively having a first and a second opening on the first and second surface, the second opening being larger than the first opening; and a plurality of abrasive particles respectively disposed in the holes and attached to the substrate via a plurality of adhesive portions, each of the abrasive particles having a tip protruding outward from the first surface and a remaining part covered with one of the adhesive portions inside the corresponding hole; wherein the first openings of the holes are smaller than the abrasive particles, and the abrasive particles are respectively retained in the holes.
 2. The grinding tool according to claim 1, wherein each of the holes includes at least a first and a second hole section connected with each other, the first hole section being opened on the first surface through the first opening, and the second hole section being opened on the second surface through the second opening.
 3. The grinding tool according to claim 2, wherein each of the holes further includes a third hole section between the first and second hole sections, the third hole section being respectively connected with the first and second hole sections.
 4. The grinding tool according to claim 2, wherein the first hole section has a tapered shape that narrows toward the first surface.
 5. The grinding tool according to claim 4, wherein a material angle between an inner sidewall of the first hole section and the first surface is between about 70 and about 89 degrees.
 6. The grinding tool according to claim 2, wherein the second hole section has an inner sidewall substantially perpendicular to the second surface.
 7. The grinding tool according to claim 1, wherein the first opening has a diameter between 0.4 mm and 0.75 mm, and the second opening has a diameter between 1 mm and 2 mm.
 8. The grinding tool according to claim 1, wherein the substrate is a single rigid body.
 9. The grinding tool according to claim 1, wherein the substrate is made of a metallic material or ceramics.
 10. The grinding tool according to claim 1, wherein the abrasive particles are made of diamond, cubic boron nitride, aluminum oxide or silicon carbide.
 11. The grinding tool according to claim 1, wherein the abrasive particles have a hexoctahedron crystalline form, and an average greatest width of the abrasive particles is between about 800 μm and about 1000 μm.
 12. The grinding tool according to claim 1, further including a base substrate having a surface provided with a cavity, the substrate being disposed in the cavity and attached to the base substrate.
 13. The grinding tool according to claim 1, wherein the adhesive portions include epoxy, phenolic resins, polyester resins, polyamide resins, polyimide resins, polycarbonate resins, and any combinations thereof.
 14. A method of fabricating a grinding tool, comprising: providing a substrate having a first and a second surface and a plurality of holes, each of the holes extending through the substrate and respectively having a first and a second opening on the first and second surface, the second opening being larger than the first opening; respectively placing a plurality of abrasive particles in the holes through the second openings thereof, wherein the abrasive particles are generally larger than the first openings and partially protrude outward from the first openings; placing the substrate on a fixed support having a plurality of positioning cavities, the abrasive particles protruding from the first openings being respectively received partially in the positioning cavities; and respectively applying a plurality of adhesive portions through the second openings into the holes, thereby the adhesive portions respectively cover the abrasive particles inside the holes and fixedly attach the abrasive particles to the substrate.
 15. The method according to claim 14, further including attaching the substrate with the abrasive particles thereon to a base substrate having a surface provided with a cavity, the substrate being disposed in the cavity of the base substrate.
 16. The method according to claim 14, wherein the positioning cavities of the fixed support have an accurately controlled depth, and the step of placing the substrate on the fixed support adjusts the positions of the abrasive particles in the holes so that the abrasive particles protrude from the first surface of the substrate with a desirable height.
 17. The method according to claim 14, wherein the step of providing a substrate having a first and a second surface and a plurality of holes includes drilling the holes into the substrate, each of the holes including a first and a second hole section connected with each other, the first hole section having a tapered shape and being opened on the first surface through the first opening, and the second hole section having a cylindrical shape and being opened on the second surface through the second opening.
 18. The method according to claim 14, wherein the step of providing a substrate having a first and a second surface and a plurality of holes includes drilling the holes into the substrate, each of the holes including a first, a second and a third hole sections connected with one another, the first hole section having a tapered shape and being opened on the first surface through the first opening, the second hole section being opened on the second surface through the second opening, and the third hole section being located between the first and second hole sections.
 19. The method according to claim 14, wherein the substrate is a single rigid body.
 20. The method according to claim 14, wherein the substrate is made of a metallic material or ceramics. 